A numerically controlled machine tool is a machine tool that is driven by using a numerical control device and is called an NC machine tool. The numerical control device includes a calculator command mechanism for ordering an operation of the machine tool, a mechanism for detecting whether the machine tool moves according to the command, and a mechanism that compares a target value to a detected value to automatically correct an error when the target value and the detected value are different from each other.
A machining order, a cutting speed, and a kind or size of cutting tool which are provided as machining conditions of a workpiece are analyzed as symbols that are expressed by specific numbers from a machining drawing. When these symbols are inputted into the control device, a command is inputted into the machine tool to operate according to the command, thereby automatically cutting the workpiece.
Numerically controlled machine tools that are produced for manufacturing a plurality of components may be applicable to cam cutting by a milling machine or a process for automatically a punching position in a boring machine. In recent years, the numerical control method may be adopted to a lathe and thus generalized. As semiconductor technologies and computers are developed, an NC machine tool in which a computer is built may be called a computerized numerical control (CNC) machine tool.
Examples of the CNC machine tool according to the related art are disclosed in Korean Patent Application No. 1996-0013171 (hereinafter, referred to as “Prior Document 1”) and Korean Patent Application No. 2009-0032675 (hereinafter, referred to as “Prior Document 2”).
According to the CNC lathe of Prior Document 1, a main shaft spindle bundle for machining a workpiece vertically and horizontally moves to automatically determine a position of a chuck for machining the workpiece. Here, a pair of guides for horizontally moving the main shaft spindle bundle is lengthily installed in a horizontal direction. The two guides are vertically spaced apart from each other. A back surface of the main spindle bundle is slidably coupled to the pair of guides.
According to the CNC lathe of Prior Document 1, which has the above-described structure, only the back surface of the main shaft spindle is supported by the guides, and a front surface is not supported. Thus, while the main shaft spindle bundle is horizontally slid, a load may be concentrated forward to interrupt smooth sliding. As a result, it may be difficult to accurately control a position of the chuck.
According to the CNC machine tool of Prior Document 2, three driving parts are vertically slid to automatically determine a position of a cutter for machining a workpiece. Here, a pair of guides for vertically sliding the three driving parts is lengthily installed in a vertical direction on a front surface of a post member. The two guides are horizontally spaced apart from each other. A back surface of the sliding member for supporting the three driving parts is slidably coupled to the pair of guides.
According to the CNC machine tool of Prior Document 2, which has the above-described structure, only the back surface of the sliding member is supported by the guides, and a front surface is not supported, like Prior Document 1. Thus, while the sliding member is vertically slid, a load may be concentrated forward to interrupt smooth sliding. As a result, it may be difficult to accurately control a position of the cutter.